Improved Dark Energy Constraints From ~ 100 New CfA Supernova Type Ia Light Curves

摘要: We combine the CfA3 supernovae Type Ia (SN Ia) sample with samples from literature to calculate improved constraints on dark energy equation of state parameter, w. The is added Union set Kowalski et al. form Constitution and, combined a BAO prior, produces 1 + w = 0.013+0.066 –0.068 (0.11 syst), consistent cosmological constant. addition makes cosmologically useful nearby SN Ia between 2.6 and 2.9 times larger than before, reducing statistical uncertainty point where systematics play largest role. use four light-curve fitters test for systematic differences: SALT, SALT2, MLCS2k2 (RV 3.1), 1.7). SALT high-redshift Hubble residuals trends versus color scatter MLCS2k2. overestimates intrinsic luminosity 0.7 < Δ 1.2. RV 3.1 host-galaxy extinction while 1.7 does not. Our investigation no bubble. also find that, after correction, in Scd/Sd/Irr hosts are intrinsically fainter those E/S0 by 2σ, suggesting that they may come different populations. have low (0.1 mag) reddening. Current errors can be reduced improving photometric accuracy, including retrain fitters, combining optical photometry near-infrared understand extinction, determining if environments give rise correction shape color.